Not using a ubiquitous language when developing an application is incurring yet another form of design debt, the overhead involved in manual testing is similar to the overhead incurred in translating between separate languages when conversations between users/domain experts and developers occur. Like with foreign languages, idiomatic assumptions and other misunderstandings are likely to fall short of a true conversation, so just pony up and focus on using a COMMON LANGUAGE as Eric Evans refers to in DDD.Me